blob: 9e1c3a3364fbaf0a031d4db26a115b528391c489 [file] [log] [blame]
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package impl
import (
"fmt"
"reflect"
"strconv"
"strings"
"sync"
"sync/atomic"
"google.golang.org/protobuf/reflect/protoreflect"
pref "google.golang.org/protobuf/reflect/protoreflect"
piface "google.golang.org/protobuf/runtime/protoiface"
)
// MessageInfo provides protobuf related functionality for a given Go type
// that represents a message. A given instance of MessageInfo is tied to
// exactly one Go type, which must be a pointer to a struct type.
type MessageInfo struct {
// GoReflectType is the underlying message Go type and must be populated.
// Once set, this field must never be mutated.
GoReflectType reflect.Type // pointer to struct
// Desc is the underlying message descriptor type and must be populated.
// Once set, this field must never be mutated.
Desc pref.MessageDescriptor
// Exporter must be provided in a purego environment in order to provide
// access to unexported fields.
Exporter exporter
// OneofWrappers is list of pointers to oneof wrapper struct types.
OneofWrappers []interface{}
initMu sync.Mutex // protects all unexported fields
initDone uint32
reflectMessageInfo
// Information used by the fast-path methods.
methods piface.Methods
coderMessageInfo
extensionFieldInfosMu sync.RWMutex
extensionFieldInfos map[pref.ExtensionType]*extensionFieldInfo
}
type reflectMessageInfo struct {
fields map[pref.FieldNumber]*fieldInfo
oneofs map[pref.Name]*oneofInfo
getUnknown func(pointer) pref.RawFields
setUnknown func(pointer, pref.RawFields)
extensionMap func(pointer) *extensionMap
nilMessage atomicNilMessage
}
// exporter is a function that returns a reference to the ith field of v,
// where v is a pointer to a struct. It returns nil if it does not support
// exporting the requested field (e.g., already exported).
type exporter func(v interface{}, i int) interface{}
// getMessageInfo returns the MessageInfo for any message type that
// is generated by our implementation of protoc-gen-go (for v2 and on).
// If it is unable to obtain a MessageInfo, it returns nil.
func getMessageInfo(mt reflect.Type) *MessageInfo {
m, ok := reflect.Zero(mt).Interface().(pref.ProtoMessage)
if !ok {
return nil
}
mr, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *MessageInfo })
if !ok {
return nil
}
return mr.ProtoMessageInfo()
}
func (mi *MessageInfo) init() {
// This function is called in the hot path. Inline the sync.Once
// logic, since allocating a closure for Once.Do is expensive.
// Keep init small to ensure that it can be inlined.
if atomic.LoadUint32(&mi.initDone) == 0 {
mi.initOnce()
}
}
func (mi *MessageInfo) initOnce() {
mi.initMu.Lock()
defer mi.initMu.Unlock()
if mi.initDone == 1 {
return
}
t := mi.GoReflectType
if t.Kind() != reflect.Ptr && t.Elem().Kind() != reflect.Struct {
panic(fmt.Sprintf("got %v, want *struct kind", t))
}
si := mi.makeStructInfo(t.Elem())
mi.makeKnownFieldsFunc(si)
mi.makeUnknownFieldsFunc(t.Elem(), si)
mi.makeExtensionFieldsFunc(t.Elem(), si)
mi.makeMethods(t.Elem(), si)
atomic.StoreUint32(&mi.initDone, 1)
}
type (
SizeCache = int32
WeakFields = map[int32]piface.MessageV1
UnknownFields = []byte
ExtensionFields = map[int32]ExtensionField
)
var (
sizecacheType = reflect.TypeOf(SizeCache(0))
weakFieldsType = reflect.TypeOf(WeakFields(nil))
unknownFieldsType = reflect.TypeOf(UnknownFields(nil))
extensionFieldsType = reflect.TypeOf(ExtensionFields(nil))
)
type structInfo struct {
sizecacheOffset offset
weakOffset offset
unknownOffset offset
extensionOffset offset
fieldsByNumber map[pref.FieldNumber]reflect.StructField
oneofsByName map[pref.Name]reflect.StructField
oneofWrappersByType map[reflect.Type]pref.FieldNumber
oneofWrappersByNumber map[pref.FieldNumber]reflect.Type
}
func (mi *MessageInfo) makeStructInfo(t reflect.Type) structInfo {
si := structInfo{
sizecacheOffset: invalidOffset,
weakOffset: invalidOffset,
unknownOffset: invalidOffset,
extensionOffset: invalidOffset,
fieldsByNumber: map[pref.FieldNumber]reflect.StructField{},
oneofsByName: map[pref.Name]reflect.StructField{},
oneofWrappersByType: map[reflect.Type]pref.FieldNumber{},
oneofWrappersByNumber: map[pref.FieldNumber]reflect.Type{},
}
if f, _ := t.FieldByName("sizeCache"); f.Type == sizecacheType {
si.sizecacheOffset = offsetOf(f, mi.Exporter)
}
if f, _ := t.FieldByName("XXX_sizecache"); f.Type == sizecacheType {
si.sizecacheOffset = offsetOf(f, mi.Exporter)
}
if f, _ := t.FieldByName("XXX_weak"); f.Type == weakFieldsType {
si.weakOffset = offsetOf(f, mi.Exporter)
}
if f, _ := t.FieldByName("unknownFields"); f.Type == unknownFieldsType {
si.unknownOffset = offsetOf(f, mi.Exporter)
}
if f, _ := t.FieldByName("XXX_unrecognized"); f.Type == unknownFieldsType {
si.unknownOffset = offsetOf(f, mi.Exporter)
}
if f, _ := t.FieldByName("extensionFields"); f.Type == extensionFieldsType {
si.extensionOffset = offsetOf(f, mi.Exporter)
}
if f, _ := t.FieldByName("XXX_InternalExtensions"); f.Type == extensionFieldsType {
si.extensionOffset = offsetOf(f, mi.Exporter)
}
if f, _ := t.FieldByName("XXX_extensions"); f.Type == extensionFieldsType {
si.extensionOffset = offsetOf(f, mi.Exporter)
}
// Generate a mapping of field numbers and names to Go struct field or type.
fieldLoop:
for i := 0; i < t.NumField(); i++ {
f := t.Field(i)
for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
n, _ := strconv.ParseUint(s, 10, 64)
si.fieldsByNumber[pref.FieldNumber(n)] = f
continue fieldLoop
}
}
if s := f.Tag.Get("protobuf_oneof"); len(s) > 0 {
si.oneofsByName[pref.Name(s)] = f
continue fieldLoop
}
}
// Derive a mapping of oneof wrappers to fields.
oneofWrappers := mi.OneofWrappers
if fn, ok := reflect.PtrTo(t).MethodByName("XXX_OneofFuncs"); ok {
oneofWrappers = fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[3].Interface().([]interface{})
}
if fn, ok := reflect.PtrTo(t).MethodByName("XXX_OneofWrappers"); ok {
oneofWrappers = fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[0].Interface().([]interface{})
}
for _, v := range oneofWrappers {
tf := reflect.TypeOf(v).Elem()
f := tf.Field(0)
for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
n, _ := strconv.ParseUint(s, 10, 64)
si.oneofWrappersByType[tf] = pref.FieldNumber(n)
si.oneofWrappersByNumber[pref.FieldNumber(n)] = tf
break
}
}
}
return si
}
// makeKnownFieldsFunc generates functions for operations that can be performed
// on each protobuf message field. It takes in a reflect.Type representing the
// Go struct and matches message fields with struct fields.
//
// This code assumes that the struct is well-formed and panics if there are
// any discrepancies.
func (mi *MessageInfo) makeKnownFieldsFunc(si structInfo) {
mi.fields = map[pref.FieldNumber]*fieldInfo{}
md := mi.Desc
for i := 0; i < md.Fields().Len(); i++ {
fd := md.Fields().Get(i)
fs := si.fieldsByNumber[fd.Number()]
var fi fieldInfo
switch {
case fd.ContainingOneof() != nil:
fi = fieldInfoForOneof(fd, si.oneofsByName[fd.ContainingOneof().Name()], mi.Exporter, si.oneofWrappersByNumber[fd.Number()])
case fd.IsMap():
fi = fieldInfoForMap(fd, fs, mi.Exporter)
case fd.IsList():
fi = fieldInfoForList(fd, fs, mi.Exporter)
case fd.IsWeak():
fi = fieldInfoForWeakMessage(fd, si.weakOffset)
case fd.Kind() == pref.MessageKind || fd.Kind() == pref.GroupKind:
fi = fieldInfoForMessage(fd, fs, mi.Exporter)
default:
fi = fieldInfoForScalar(fd, fs, mi.Exporter)
}
mi.fields[fd.Number()] = &fi
}
mi.oneofs = map[pref.Name]*oneofInfo{}
for i := 0; i < md.Oneofs().Len(); i++ {
od := md.Oneofs().Get(i)
mi.oneofs[od.Name()] = makeOneofInfo(od, si.oneofsByName[od.Name()], mi.Exporter, si.oneofWrappersByType)
}
}
func (mi *MessageInfo) makeUnknownFieldsFunc(t reflect.Type, si structInfo) {
mi.getUnknown = func(pointer) pref.RawFields { return nil }
mi.setUnknown = func(pointer, pref.RawFields) { return }
if si.unknownOffset.IsValid() {
mi.getUnknown = func(p pointer) pref.RawFields {
if p.IsNil() {
return nil
}
rv := p.Apply(si.unknownOffset).AsValueOf(unknownFieldsType)
return pref.RawFields(*rv.Interface().(*[]byte))
}
mi.setUnknown = func(p pointer, b pref.RawFields) {
if p.IsNil() {
panic("invalid SetUnknown on nil Message")
}
rv := p.Apply(si.unknownOffset).AsValueOf(unknownFieldsType)
*rv.Interface().(*[]byte) = []byte(b)
}
} else {
mi.getUnknown = func(pointer) pref.RawFields {
return nil
}
mi.setUnknown = func(p pointer, _ pref.RawFields) {
if p.IsNil() {
panic("invalid SetUnknown on nil Message")
}
}
}
}
func (mi *MessageInfo) makeExtensionFieldsFunc(t reflect.Type, si structInfo) {
if si.extensionOffset.IsValid() {
mi.extensionMap = func(p pointer) *extensionMap {
if p.IsNil() {
return (*extensionMap)(nil)
}
v := p.Apply(si.extensionOffset).AsValueOf(extensionFieldsType)
return (*extensionMap)(v.Interface().(*map[int32]ExtensionField))
}
} else {
mi.extensionMap = func(pointer) *extensionMap {
return (*extensionMap)(nil)
}
}
}
func (mi *MessageInfo) GoType() reflect.Type {
return mi.GoReflectType
}
func (mi *MessageInfo) New() protoreflect.Message {
return mi.MessageOf(reflect.New(mi.GoReflectType.Elem()).Interface())
}
func (mi *MessageInfo) Zero() protoreflect.Message {
return mi.MessageOf(reflect.Zero(mi.GoReflectType).Interface())
}
func (mi *MessageInfo) Descriptor() protoreflect.MessageDescriptor { return mi.Desc }